1. Field of the Invention
The present invention relates to open end wrenches and more particularly to an open end wrench with improved holding characteristics.
2. Description of the Prior Art
Head of a conventional open end wrench is shown in FIGS. 1 to 4 comprising three projections 20, 21, and 22 at one arm 10 and an arcuate section 41 at the other opposite arm 40. Each of projections 20, 21, and 22 has a first interior surface 23 at one side and a second interior surface 24 at the other side. A hexagonal nut (or bolt head) engages with a point on arcuate section 41, first interior surface 23, and second interior surface 24. As shown in FIG. 3, only a point on arcuate section 41 is engaged with the arcuate portion 301 of angle 30 of nut. Further as shown in FIG. 4, only side 32 is engaged with the first interior surface 23 while side 31 is at a point contact with the first interior surface 24. In view of above, the engagement is not secure. Thus a slip may occur between wrench and nut when user holds and turns the nut by the wrench. Thus, improvement exists.
It is an object of the present invention to provide an open end wrench having a head comprising a first arm comprising a first, second, and third projections each having a first interior surface at one side and a second interior surface at the other side; and an opposite second arm comprising a first, second, and third flats. A first distance between the first flat and the first interior surface of the first projection is smaller than a second distance between the second flat and the first interior surface of the second projection, a third distance between the third flat and the first interior surface of the third projection is larger than the second distance between the second flat and the first interior surface of the second projection, and an angle xcex8 is formed between one side of a held fastener and the second interior surface of one of the first, second, and third projections. By utilizing this, a fastener (e.g., nut) is secured when held by the wrench. Also, such small angle xcex8 ensures torque to be completely transferred to nut while turning wrench. Hence, a slip between wrench and nut in operation as experienced in prior art is eliminated.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.